There may have been some sense in which Atom Egoyan intended his new film to be bizarre. But surely not bizarrely acted, bizarrely written, bizarrely directed and bizarrely, completely and culpably misjudged?

The theme which Egoyan is mishandling is a very serious one: child sex abuse. His drama is about a couple living in Niagara Falls, Ontario: Matthew (Ryan Reynolds) and Tina (Mireille Enos). Their nine-year-old daughter Cassandra is taken from Matthew's parked truck, while he is in a store for just a few minutes buying food. She vanishes without trace but some years later, the cops on the case, Nicole (Rosario Dawson) and Jeffrey (Scott Speedman) pick up a sensational lead: in the course of their gruelling and sickening work trawling through the internet images circulated by paedophiles they find evidence not merely that Cassandra is alive in captivity but that the head of this paedophile ring has somehow used his contacts in the construction and property business to rig up surveillance cameras, spying on Tina's own private anguish — a horrible new refinement of voyeurism and cruelty.

As a straight procedural, this might have worked if Egoyan did not try the audience's patience and insult their intelligence with how utterly implausible his drama is. But line by line, scene by scene, it is offensively preposterous and crass. The film doesn't convince as a conventional thriller, and as some kind of dream-like fantasy of noir evil, it is frankly dubious. Rosario Dawson's cop is supposedly the figurehead for some charity which has something to do with her police work (but what, exactly?) So she attends a fancy ball in a sexy Cinderella gown, and is then kidnapped by some black-wigged villainess working for the vengeful paedophiles — by slipping a mickey finn into her drink! Huh? Has a grownup person written this script? It is embarrassingly unconvincing.

The real nadir comes when the paedophile actually allows Matthew a face-to-face meeting with the now teenage Cassandra: he sets up a meet in a remote and snowy spot. Father and daughter embrace but when Matthew shows signs of wanting to take Cassandra away, the concealed bad guy shoots him with a stun-dart. Was there a scene in which Matthew wakes up, befuddled, to find Cassandra gone? I may have missed it. I felt like I had been shot with a stun-dart myself.

Then there is the appalling acting — although to be fair to the performers, they were left floundering by the fatuous script. Kevin Durand plays the evil Mika, a guy with greying hair and an unwholesome obsession with Mozart's Magic Flute. Scott Speedman does a lot of smouldering, brooding and punching people's lights out. Rosario Dawson looks as if she is from another film entirely. And Arsinée Khanjian has an abysmal cameo in which her fluttering mannerisms are entirely unwatchable.

It looks worryingly as if Egoyan has taken a serious issue and burdened it to breaking point and beyond with his own indulgent, naïve and exploitative fantasies. Three years ago, Cannes presented a film by Markus Schleinzer, Michael, which showed that with sufficient clarity and courage, these unthinkably shocking ideas can work as cinema. Sadly, Egoyan's film is simply a tangled and conceited mess.